This invention relates to fastening tubes to walls, including but not limited to electromagnetic shielding for holes made in walls comprised of composite materials.
Electromagnetic energy may adversely affect electronic equipment depending on the level and frequency of such energy. Electromagnetic energy is a concern for ships, vessels, aircraft, buildings, and other types of structures, whether military or commercial, that utilize electronic equipment. The structure of the ships, vessels, aircraft, buildings, and other types of structures must have penetrations or vias, which are holes placed in a structure to allow distributed systems, such as air, water, power, communications, and so forth, to pass into and through a space or compartment. Although these penetrations allow cables, pipes, vents, light, and so forth to pass through a structure, these penetrations also permit electromagnetic energy to pass.
Due to the conductive nature of metal, the material most often used in the construction of ships, the electromagnetic energy may be reduced in penetrations using conventional methods such as stuffing tubes, pipe penetrations, and flanges for ventilation, all of which may be welded. Steel, however, corrodes, thereby reducing the life of the object formed from steel.
Today""s ships, aircraft, and other vessels are being manufactured using composite structures as a building block for many of these vessels. Examples of material used in composite structures include fiberglass, e-glass, vinyl esther, polyurethane, carbon fiber, glass or wood core, resins, and so forth. Composite structures tend to be corrosion-resistant because composite structures are nonmetallic, and hence do not rust. As a result, however, composite structures do not provide electromagnetic protection unless they have a conductive material built into the composite structure to provide electromagnetic shielding. Such a material is typically built on the inner part of the composite structure, so that the conductive material, which tends to be metal, is not exposed to the elements and thus will not rust. This conductive material is typically grounded to provide a path for the electromagnetic energy to be dissipated.
Because locations that have electronic equipment that is sensitive to electromagnetic energy should be properly protected from electromagnetic energy, the electromagnetic energy levels need to be maintained within allowable limits. Because electronic equipment and other devices are typically routed to most compartments in a ship, aircraft, or vessel, it is likely that a cable, pipe, or other type of system will need to pass through the structure, thereby placing an opening in the protective layer of shielding that is placed within the composite structure and allowing electromagnetic energy to pass through the penetration in the structure.
Methods that require exposing the grounding material in a composite structure typically utilize a pre-processing step that requires grinding, sanding, or some other method to expose the conductive grounding material within the composite structure. Because the conductive grounding material is encased within a resin that is part of the composite structure, exposing the grounding material is usually very difficult and time-consuming process to adequately access the grounding structure within the composite material.
Accordingly, there is a need for a method and apparatus for providing electromagnetic protection for penetrations through composite structures that is not difficult nor time-consuming and, if possible, avoids pre-processing.